1. Field of the Invention
The present invention relates to automatically changeable display signs.
2. Description of the Prior Art
It has long been recognized that visual display of advertising material to high concentrations of the purchasing public has substantial benefit in promoting the message or product being advertised. Consequently, there is a great demand for placement of visual advertising at locations frequented by the purchasing public. Due to the space limitations for advertising, as by billboards located along a frequently travelled thoroughfare or at public gatherings, great efforts have been made to provide display means which is effective to sequentially display different advertising messages to the assembled public or passerby.
Such efforts have led to the development of display devices which present elongated parallel prisms disposed in side-by-side relationship for selective rotation in unison to sequentially display the three faces of the respective prisms for exposing advertising indicia located on such faces to thereby exhibit a composite message or advertisements. A device of this type is shown in U.S. Pat. No. 4,073,081. While satisfactory for its intended purposes, devices of this type suffer the shortcoming that they are restricted in their capacity to store and display different messages.
Other efforts have led to the development of devices which incorporate scrolls having multiple advertisements thereon but such devices suffer the shortcoming that they are relatively unwieldly, expensive to install and are subject to damage from weather and climatic conditions. One example of these styles of devices is shown in U.S. Pat. No. 4,489,514.
Other devices have been proposed which incorporate a carrousel, or rotary panel arrangement, such as that shown in U.S. Pat. Nos. 3,696,536, 1,294,130, 1,050,936, 801,133, 793,348, 793,701 and 522,979. Many of the devices shown in these patents suffer the shortcoming that they are limited in capacity and incorporate relatively complex mounting and drive mechanisms which are expensive to manufacture and have frequently proven unreliable in operation.